The invention relates to a cylinder head gasket and more particularly to a cylinder head gasket for use in relatively large engines (as compared to passenger car engines) and primarily for use in so-called large-scale engines as are employed on trucks, construction machinery and the like and are prone to heavy soiling in use of such vehicles and machines. These large engines can have a single cylinder head that extends over all combustion chambers/cylinders of a cylinder block (also called crankcase) or of a cylinder bank of a V-type engine and a single cylinder head gasket dedicated to said cylinder head or can have a separate cylinder head and a separate cylinder head gasket for each cylinder.
With these engines, the so-called seal gap that exists between the cylinder head and the cylinder block, the latter usually containing cylinder liners, and that is to be sealed by the cylinder head gasket has a relatively large height/width, generally amounting to approximately 1.2 mm to approximately 5 mm, and with an engine presenting such a wide seal gap there is a particularly high risk when the engine is operating or also when it is being cleaned, such cleaning being undertaken frequently and usually using a high-pressure cleaner, of contaminants getting into the seal gap, in particular solid particles such as dust and other dirt, but also liquids such as splashes of water getting on the engine while in operation or splashing water used in engine cleaning and usually having some detergent added thereto. It is therefore necessary for the seal gap to be sealed by the outer perimeter portion of the cylinder head gasket, and for that purpose it is known in the case of a single-layered cylinder head gasket from ElringKlinger AG, i.e., a cylinder head gasket having only a single metallic gasket layer and being configured as a so-called gasket for a single cylinder, to apply in the immediate vicinity of the outer perimeter margin of the gasket layer on each of the two sides thereof an elastomeric sealing element which is in the shape of an elastomeric sealing material bead (so-called sealing lip) and extends around the gasket layer in the immediate vicinity of the outer perimeter margin thereof.
In the case of this known cylinder head gasket, but also in the case of multi-layered metallic cylinder head gaskets incorporating such a gasket layer having peripheral elastomeric sealing elements as well as in the case of correspondingly configured single-layer and multi-layer cylinder head gaskets including several combustion chamber through-openings, there is however the following problem: It cannot be entirely excluded that, when the engine is operating, gas or liquid leakage, albeit small, may occur around one or more combustion chamber through-openings and/or through-openings for cooling water and/or for engine oil and that consequently pressure would build up, induced by said gas or liquid leakage, in the seal gap region which is located between the cylinder head gasket and the cylinder head and/or cylinder block and is enclosed by the peripheral sealing elements if said seal gap region is, on one or both sides of the gasket layer, gas and liquid-tightly sealed, i.e., a sealed to the outside, by use of peripheral, circumferential and endless sealing elements, i.e., sealing elements closed in themselves. Therefore, in the above-mentioned known cylinder head gasket from ElringKlinger AG each of the peripheral elastomeric sealing elements is interrupted at one, i.e., only at one, location—when seen in a plan view of the cylinder head gasket, each of these peripheral elastomeric sealing elements has two end regions which, when viewed from the outer perimeter margin of the gasket layer, overlap each other and extend at an extremely small distance from each other so that said seal gap region is, both between the cylinder head and the cylinder head gasket and between the latter and the cylinder block, open to the outside at that one location, thereby preventing said pressure buildup.
However, this break in each of said peripheral circumferential elastomeric sealing elements is an entrance that, albeit localized, may permit dirt and/or liquid from the outside to get into the areas of the seal gap that are located rearward of the peripheral sealing elements, particularly during an engine cleaning procedure using a high-pressure cleaner.
The present invention aims to at least minimize this problem (object of the invention).